Process of forming accumulator-electrodes.



No. 726,468. PATBNTED APR. 28, 1903.

G. J. SCOTT. PROUESS OF FORMING AGOUMULATOR ELECTRODES.

APPLICATION FILED FEB. 28, 1903. NO MODEL.

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GORDON JOHN SCOTT, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR. TO CHARLESII. GRAHAM AND GEORGE DLBONTON, OF PHILADELPHIA,

PENNSYLVANIA.

PROCESS OF FORMING AC-CUMULATOR- -ELECTRODES.

SPECIFICATION" forming part of Letters Patent No. 726,468, dated April28, 1903.

Application filed February 28. 19.03. Serial-No. 145,597. (Nospecimens.)

T0 (ti/Z whom, it may concern:-

Be it known that I, GORDON .ToHN Scorr, a

The object of my invention is to form.

aceumulator-electrodes by a process such that after the electrodes havebeen formed and are ready for commercial use they shall be capable ofstoring a much greater electrical charge per unit weight of theelectrode than has heretofore been possible by the customary formin gprocesses.

The meaning which those skilled in the art attach to the words formingprocess is clear and well defined, even though the precise chemical andelectrical reactions which go on in the forming process may not beperfectly understood. The fact is that whether the accumulator is of thePlante or Faure type or is a combination of the two types it is thecommon practice to subject the accumulator-electrodes to a preliminaryor forming operation. This preliminaryor forming operation gets theaccumulator-electrode ready for its commercial use-that is to say, itgets it vready to receive and store a much greaterquantity of electricalenergy than would be the case if the electrode had not first beenformed. I need hardly add that I use the wort storing as applied toelectricity'in its every-day sense as employed in the accumulator art.

In the Plante accumulator the preliminary forming process consists inpassing a current through the accum ulator-electrodes for ashort timeand then either permitting the electrodes to give 0E current or passingcurrent therethrough in the opposite direction, this cycle beingrepeated a number of times and the length of time occupied by each cyclebeing increased at each repetition. In the Faure accumulator it iscustomary to form the electrodes by passing current therethrough in agiven direction and then permitting the eleo trodes to give on. current,this operation being repeated but a small number of times. In eithercase, however, the preliminary forming operation produces accumulatorelectrodes which are capable of storing a far greater quantity ofelectrical energy than would have been the case had they not beensubjected to the forming operation. It is thus seen that the formingoperation is sharply differentiated from the subsequent charging anddischarging of the accumulator in its actual use. The preliminaryforming operation changes the mechanical and chemical condition of theelectrodes into one which enables them to store a large quantity ofelectrical energy. The subsequent charging and discharging of theaccumulator in its actual use, on the otherhand, gradually disintegratesthe electrodes and makes them unfit to store electrical energy.

My invention relates to a new forming process; and its object, as hasbeen indicated above, is to devise a forming process which shall produceaccumulator-electrodes that are capable of storing a greater quantityofelectrical energy than can be stored by electrodes of the same weightformed by other processes.

To this end my forming process consists in separating theaccumulator-electrodes during the forming operation by acurrent-conducting baffle or partition, which is interposed between theelectrodes in such a manner that it will enable electric current to passdirectly from one electrode to the adjacent electrode through thecurrent-conducting baffle or partition and will permit the electrolyteto pass from one electrode to the other, but will compel this passage oftheelectrolyte to be along devious or circuitous paths.

In the drawings, Figure 1 represents a plan of the apparatus used. Fig.2 represents a vertical section along the line 2 2 of Fig. 1. Fig. 3 isa section of the line 3 3.

The structure of the cell which is to be used in my forming process is,generically considit is permitted to pass from one electrode to theother, is compelled to do so by seeking a circuitous path. At the'sametime in order that I may be enabled to subject a number of electrodes tothe forming operation in one cell at the same time I have somewhatchanged the mechanical construction of the parts as indicated in thedrawings. carrying out my new forming process to use a large cell ortrough B, at each end of which I place a spacing-wall 0, made ofelectricallyinsulating material and containing a number of grooves O.Spaced apart and held in fixed relative positions by the grooves O ofthis spacing-wall C are my current-conducting baffles or partitions A.Between each adjacent two of the on rrent-conducting bafiles I place theaccumulator-electrodes D orD, and I have used the letter D to designatethe negative accumulator-electrodes and the letter D to designate thepositive accumulator electrodes. The several negative electrodes D areelectrically connected by casting thereon an electrically-conductingbridgepiece (I, to

which bridge-piece the negative terminal d is connected in any suitablemanner. A similar bridge-piece electrically connects the positiveaccumulator-electrodes. These conducting bridge-pieces are thosecommonly used in electrical accumulators employing a large number ofelectrodes connected in parallel circuit. A top 6 (not shown in Fig. 1)is employed to prevent splashing.

The spacing-walls 0, together with the current-conducting partitions A,and the positive and negativeelectrodesDD,withtheirbridgepieces andterminals, together constitute a structure which is placed in the cellor trough B, but is held above the bottom of the cell by the ribs E. Inthis manner it will be seen that the electric current or part of it maypass directly from one electrode to the electrode adjacent thereto bygoing through the current-conductingbaflieorpartition. Theelectrolyte,on the other hand, although it is permitted to pass from one electrodeto the other, must pass in a circuitous path from the spaces between thebaffles and electrodes either along the bottom of the cell under thebaffles or along the top of the cell over the baffles.

It is to be noted at this point that it is important to have the baffleimperfo'rate, so that none of the electrolyte shall be permitted to passdirectly from one electrode to the other, as would be the case if therewere apertures through the battle. The utility of my process, in fact,decreases very rapidly it the baffles employed in its execution aresupplied with even small perforations.

Such being the structure of the apparatus which I employ, my preliminaryor forming process will be readily understood. The electrodes D D arethe same as those now in common commercial usethat is to say, they aremade of lead or other substances, as copper, palladium, tice.-and theymay be supplied with active material, such as red lead I prefer, infact, in

and litharge, as in the Faure type of cell, or with other appropriateactive materials when other-types of accumulators are employed. In theforming operation I pass the preliminary or forming current from one ofthe terminals of the cell which I have just described through theelectrolyte and the baffle or battles to the other terminal of the cell,and after the lapse of a certain period of time the further passage ofcurrent is stopped and the cell is either permitted to discharge or hascurrent passed through it in the reverse direction. This cycle ofoperations is repeated a number of times suficient to properly form theelectrodes,when the electrodes will be found to be in condition forcommercial usethat is, to store electrical energy by being charged anddischarged. Except for the interposition of the current-conductingbailie all this is in accordance with the usual practice. Thepeculiarity about my forming process, however, consists in this, thatwhereas in the old forming processes electrically nonconducting andperforated partitions have been used between the electrodes I use aconducting-partition, and the remarkable fact is that by this change inthe forming process I produce accumulator-electrodes of in creasedstorage capacity.

The current-conducting baffle which has been described throughout thisspecification has, as stated above, been heretofore used in the normaloperation of primary and secondary batteries. When used in secondarybatteries, it has been peculiarly efficient in the charging anddischarging operation in decreasing the internal resistance of thebattery, in preventing local action, and in increasing the ratio ofelectrical energy discharged to the electrical energy chargedthat is, inincreasing the efficiency of the battery. I have discovered that byutilizing this current-conducting battle, not in the process of chargingand discharging the accumulator in its ordinary commercial use, but inthe original process of forming the electrodes, I produce a result nothitherto produced-mamely, an accumulator-electrode which has a greaterstorage capacity per unit of weight than would otherwise be the case.

In the ordinary forming processes it is necessary to use a comparativelylow voltage for the forming-current, which voltage is increased verygradually as the plate is being formed. In my forming process I amenabled to use somewhat higher voltages for the forming-current and toincrease these voltages somewhat more rapidly without inj urious effecton the electrodes under formation and without undue heat or energylosses. Additionally, my forming process produces a formed electrodewhich is more dense and smooth, and therefore better adapted forsubsequent use than those produced by the old forming processes.

I have described my process as carried out in an apparatus in whichseveral positive and several negative accumulator-electrodes are formedsimultaneously; but manifestly I may use my process to form one or morepositive electrodes only or to form one or more negative electrodesonly. In this case there would be contained in the forming-cell one ormore electrodes of a given sign which were being formed and one or moreopposed electrodes of the opposite sign which were not being formed, butwhich merely supplied the electrochemical conditions necessary to theformation of the first-mentioned electrodes. My claims are to beconstrued as covering both forms.

I claim 1. The process of formingan accumulator-electrode which consistsin separating it from the opposed electrode during the forming operationby a current-conducting baflle, substantially as described.

2. The process of forming an accumulator-electrode which consists inpassing the forming, current through a cell containing the electrode tobe formed and an opposed electrode separated therefrom'by acurrentconducting baffle, substantially as described.

3. The process of forming an accumulator-electrode, which consists inseparating, it

during the forming operation, from the opposed electrode by acurrent-conductin g baffle which enables electric current to passdirectly through the baffle from one electrode to the other and theelectrolyte to pass between the electrodes along circuitous paths only,substantially as described.

4. The process of forming an accumula: tor-electrode composed of leadand active material which consists in separating it during the formingprocess from the opposed electrode by a current-conducting baffle,substantially as described.

5. The process of forming an accumulator-electrode composed of lead andactive material which consists in passing the forming current through acell containing the electrode to be formed and an opposed electrodeseparated therefrom by a current-conducting bafile, substantially asdescribed.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses.

. GORDON JOHN SCOTT.

